For a while in the early 2000s, Apple devices all used industry standard connectors, but Monoprice probably paid a part in changing that
I love +Monoprice and it's my go-to site to buy cables and accessories of all sorts. However, I wouldn't be at all surprised if the rise of Monoprice is part of the reason that today's iPhones and iPods use a proprietary connector instead of the standard micro-USB found on virtually every other mobile device.
Apple is the most profitable tech company in the world and not so long ago Best Buy was also very profitable. One of the key's to Best Buy's profits was selling ridiculously over-priced cables and other accessories along side no-margin TVs. I wouldn't be at all surprised if Apple recognized the trend toward generic connectors early. A decade ago, Mac laptops had standard DVI video outputs, Firewire and USB. DVI was eventually supplanted by the mini-display-port which was smaller (good) and unique to Apple at first (bad). Similarly iPods went from Firewire to the 30 pin dock and now the Lightning connector.
By using proprietary connectors, Apple can charge a premium for its own connectors and extract a tax from any other company that wants to get into the business of hooking up to its devices, which is bad for consumers.